Conducting plug target and method of making the same



30, 1965 s. T. YA NAGI$AWA 3,221,199

CONDUCTING PLUG TARGET AND METHOD OF MAKING THE SAME Filed Aug. 30, 1961 lo l/ INV EN TOR.

. SAM EL T. YANAGISAWA AGENTS United States Patent 3,221,199 CONDUCTING PLUG TARGET AND METHOD OF MAKING THE SAME Samuel T. Yanagisawa, Westport, Conn., assignor to The Machlett Laboratories, Incorporated, Springdale, Conn., a corporation of Connecticut Filed Aug. 30, 1961, Ser. No. 134,962 8 Claims. (Cl. 313-89) This invention relates to conducting plug targets and more specifically to a target structure having particular applicability to television pickup electron discharge devices and a method of making the target structure.

One type of television pickup device is known as an image orthicon. As broadly defined, an image orthicon is a camera tube in which an electrical image is produced by a photo-emitting surface and focused on a separate storage target, which target is scanned on its opposite side by a low velocity electron beam.

In this instance, the front side of the image orthicon tube is a transparent plate upon which an optical image is focused. On the inside of the front plate there is usually a photocathode that releases electrons in direct proportion to the brightness of the image projected thereon. These photoelectrons are accelerated and focused on the target so as to create a charge pattern on the target that is also in direct proportion to the brightness of the image.

The prior art targets capacitively couple the image charge to the other side of the target. It therefore requires that the target material have a low lateral resistivity to prevent leakage of the image charge across the face and must also be thin enough to provide good coupling of the image charge to the scanning side of the target.

To avoid the need for thin, very fragile glass discs of the order of to 10 wavelengths of light thickness as presently used in the art, I propose to utilize a target that is made of insulating material having conducting plugs extending from one side of the target to the other to directly couple the signals on one side of the target to the scanning beam which is on the other side thereof.

I have found that certain thin metal films which have been oxidized or fluoridized are particularly tough and flexible and allow repeated handling during the process of manufacture and, in addition, makes an excellent dielectric film useful as a target in a storage device.

It is, therefore, a principal object of the present invention to provide a durable target structure.

It is another object of the present invention to provide a target structure haviiig a required dielectric constant.

It is still another object of the present invention to provide a target structure that is capable of being easily reproduced on a mass produced scale.

The features of my invention which I believe to be novel are set forth with particularity in the appended claims. The invention itself, however, both as to its organization and method of operation, together with further objects and advantages thereof, may best be understood by referring to the following description taken in conjunction with the accompanying drawing in which the figure represents an exaggerated, partial cross-sectional view of the target structure of my invention immediately after being formed by one of the processes hereinafter described.

Referring now to the drawing, there is shown my novel target mounted on a suitable support member 10 which may serve as a support to carry on the steps of my process. Support member 10 has a strippable lacquer base substrate 12 mounted thereon. The surface of base 10 action in that they are not capable of being oxidized or fluoridized. Deposited over the dots 20 and the substrate 12 is a continuous fihn generally designated as 13 and composed of sections 14 and 18 (thickness ZOO-20,000 A.). This film 13, in its initial state, is a metallic substance that is noted for its ability to become oxidized and fluoridized and thus exhibit dielectric properties. A second set of dots or islands 16 is deposited on those portions of film 13 which are in registry with prior dots 20.

Having formed these islands or dots with an intermediate oxidizable layer, I have found that if the exposed portions 14 of film 13 are now fluoridized or oxidized completely, those areas 14, which lie outside the bounds of dots 16 and 20, will new exhibit dielectric properties Those areas of film 13 which lie between dots 16 and 20,- namely portions 18, will still retain their conducting capabilities since they have not been exposed to the fluoridation or oxidation means and, therefore, have not had an opportunity to become dielectric. Thus,'I am able to produce a thin membrane of insulating material that is pierced by continuous metallic islands.

Base member 10, while shown as glass is required to have a surface that is optically flat and smooth. Whi e this has been depicted as glassy material, it will be obvious to those skilled in the art that other materials may also be used provided that they meet the requirements of flatness.

On the flat surface of supporting structure 10 the strippable substrate 12 is placed and may consist of any strippable film material. I have found that a lacquer base film, for example, cellulose nitrate or polystyrene, is admirably suited for this type of operation. It should be understood that substrate 12 should be of uniform thickness and should be easily stripped from both the supporting surface and the target itself. A plurality of dots 20 is deposited on film 12 and may be formed by evaporating nonoxidized material through a foraminous mask (not shown) which is capable of being replaced in exact registry for a subsequent operation. The dots 20 may be deposited in any thickness ranging from about 2,000 to 20,000 angstroms. The dots 20 may be applied by either spraying or evaporating the material through the mask. The mask is then removed and a uniform layer 13 of either aluminum or copper or any other readily oxidizable or fluoridizable material may be deposited over the dots 20 and substrate 12. The foraminous mask is then replaced so that the openings therein are in exact registry with the prior dots 20, and dots 16 are then deposited.

To complete the process, the entire assembly is then dipped or placed in an oxidizing or fluoridizing atmosphere whereupon the exposed portions 14 of film 13 are completely oxidized or fluoridized and become dielectric. The completed target assembly may now be stripped from substrate 12 and applied as a target electrode in a suitable storage tube.

As an alternative method or process of manufacturing my novel target assembly, I have found that it is also possible to strip the assambly from base member 12 after the dots 16 have been applied. By so doing, the fluoridizing or oxidizing process may be hastened since the fluoride or oxide may be applied from both sides and thereby insure a greater penetration and a noticeable shortening of the time required to oxidize or fluoridize film 13.

By performing the above steps, I am able to produce sections 14 which exhibit dielectric characteristics while sections 18 are still highly conductive since they have not been exposed to the dielectric forming step.

I have found that gold, platinum, chromium, rhodium, and nickel are very well suited for use as dots or islands 16 and 20. However, I do not wish to be so limited since it will be obvious to those skilled in the art that various other nonoxidizable metals may be used in place thereof.

While there have been described what are presently considered the preferred embodiments of my invention, it will be obvious to those skilled in the art that various other changes and modifications may be made therein without departing from the inventive concept, and it is aimed in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of this invention.

What I claim is:

1. A method of forming a target structure comprising the steps of forming a first plurality of chemically nonreactive conductors, depositing a chemically reactive continuous film over the first plurality of conductors, depositing a second plurality of chemically nonreactive conductors on the film in registry with the first plurality of conductors and chemically treating the exposed portions of the film to convert the exposed portions to a dielectric.

2. The method of claim 1 wherein the nonreactive conductors comprise metallic portions selected from the group consisting of gold, platinum, rhodium, chromium and nickel.

3. The method of claim 2 wherein the chemically reactive film is converted to a dielectric by treatment with a chemical from the group consisting of oxides and fluorides.

4. The method of claim 3 wherein the chemically reactive layer comprises a metallic film selected from the group consisting of aluminum and copper.

5. A target structure for the storage of electrical charges, comprising a continuous metal film, and a plurality of discreet spaced conductive metal elements on both sides of the metal film, each of the metal elements on one side of the film being located in register with a respective met-a1 element on the other side of the film, the portions of the film located between registering elements being electrically conductive while the exposed areas of the film surrounding said elements are nonconductive.

67 A target structure according to claim 5 wherein the conductive metal elements are of a chemically nonreactive metal.

7. A target structure according to claim 6 wherein said exposed areas of the film are metal converted to a dielectric.

8. A target structure according to claim 6 wherein the nonreactive metal is selected from the group consisting of gold, platinum, chromium, rhodium and nickel.

References Cited by the Examiner UNITED STATES PATENTS 2,588,019 3/1952 Law 313-89 X 2,945,973 7/1960 Anderson 313-66 X 2,963,604 12/1960 Weimer 313-66 2,976,188 3/1961 Kohl 117-212 2,981,611 4/1961 Ashworth 117-212 2,999,177 9/1961 Null et al. 313-66 HERMAN KARL SAALBACH, Primary Examiner.

ARTHUR GAUSS, GEORGE N. WESTBY, Examiners. 

1. A METHOD OF FORMING A TARGET STRUCTURE COMPRISING THE STEPS OF FORMING A FIRST PLURALITY TO CHEMICALLY NONREACTIVE CONDUCTORS, DEPOSITING A CHEMICALLY REACTIVE CONTINUOUS FILM OVER THE FIRST PLURALITY OF CONDUCTORS, DEPOSITING A SECOND PLURALITY OF CHEMICALLY NONREACTIVE CONDUCTORS ON THE FILM IN REGISTRY WITH THE FIRST PLURALITY OF CONDUCTORS AND CHEMICALLY TREATING THE EXPOSED PORTIONS OF THE FILM TO CONVERT THE EXPOSED PORTIONS TO A DIELECTRIC.
 5. A TARGET STRUCTURE FOR THE STORAGE OF ELECTRICAL CHARGES, COMPRISING A CONTINUOUS METAL FILM, AND A PLURALITY OF DISCREET SPACED CONDUCTIVE METAL ELEMENTS ON BOTH SIDES OF THE METAL FILM, EACH OF THE METAL ELEMENTS ON ONE SIDE OF THE FILM BEING LOCATED IN REGISTER WITH A RESPECTIVE METAL ELEMENT ON THE OTHER SIDE OF THE FILM, THE PORTIONS OF THE FILM LOCATED BETWEEN REGISTGERING ELEMENTS BEING ELECTRICALLY CONDUCTIVE WHILE THE EXPOSED AREAS OF THE FILM SURROUNDING SAID ELEMENTS ARE NONCONDUCTIVE. 